Allergens Prevalence among Patients with Respiratory Allergies in Mashhad, Iran.

Background: Respiratory allergies are among the most common allergies in the world with an increasing number of people affected in recent decades. Determination of allergens prevalence in each area is considered as the first step in prevention of allergic diseases and developing novel and more effective immunotherapies. The aim of this study was to determine the prevalence of the most common allergens among patients with respiratory allergies in Mashhad, Iran Materials and Methods: This cross sectional study included 1246 people who were referred to Allergy Clinic of Mashhad University of Medical Sciences with respiratory allergic symptoms from 2012 to 2017 in which a questionnaire containing demographic information was completed and Skin Prick Test was performed for each patient. Results: Among 1246 patients with respiratory symptoms, there were 1084 patients with allergic rhinitis (87%), 69 patients with allergic asthma (5.5%), 14 patients with allergic rhinoconjunctivitis (1.1%) and 79 patients with both allergic rhinitis and asthma (6.3%) with an overall male to female ratio of 1.18. Rhinorrhea (86.3%), sneezing (81.1%) and itchy eyes (68.4%) were the most common symptoms in patients with respiratory allergic disorders in this study and the highest rate of sensitivity was to pollens including Salsola kali (82.3%), pigweed mix (65.1%), tree mix (51.7%) and ash (49.8%), respectively. Conclusion: Generally, Salsola kali seems to be the main allergen in different respiratory allergies including allergic rhinitis, asthma and rhinoconjunctivitis in semi-arid climate of Mashhad, Iran.


INTRODUCTION
Any substance capable of inducing production of immunoglobulin E (IgE) in a genetically predisposed individual is referred to as 'allergen' (1,2). Allergens associated with animals, cockroaches, House Dust Mites (HDMs), foods, fungi, pollens, latex, and venom have been reported to be the most important factors initiating allergic responses with pollens as the most likely source of outdoor allergens and HDMs as the most common source of indoor allergens (3,4). Pollen allergens, the male gametophyte of trees, weeds and grasses, are dust-like particles released through the pollination processes. Allergies associated with pollen particles follow a seasonal pattern, since pollens are only released in specific seasons and trigger allergic responses as they find their way through nose and bronchial airways (2,3). Animal allergens and fungi are also considered the outdoor sources of allergens; however, some fungi species (Aspergillus species) can be found in warm and humid places inside either (5,6). Different types of allergic diseases are also adversely affected by HDMs which usually abound indoors, in house furniture, and live in close contact with humans (2,7,8).
Allergic diseases have been defined as hypersensitivity disorders of the immune system as the result of allergic inflammation induced by an allergen (9)(10)(11). Identifying common allergens in each area is of great importance as avoiding allergens is the first-line prevention in controlling allergic diseases (3). Moreover, it leads to a better understanding of possible reasons for allergic symptoms in sensitive people, as well as more efficient diagnosis and treatment of a specific allergy (3,10).
Physical examination, studying the history of patients, and some paraclinical tests usually helps with diagnosis of allergic disorders (9,10).The Skin Prick Test (SPT) is a diagnostic test, routinely used for assessment of IgEmediated sensitization to various allergens and is considered to provide one of the best combinations of sensitivity and specificity (9)(10)(11).The SPT is done through administration of standard commercial extracts of allergens on the forearm using a sterile lancet. The results are observed after 15 minutes in which a wheal with a 3 mm diameter greater than the negative control (saline) is considered positive (12).
Respiratory allergies are among the most frequent types of allergy in the world with an increasing incidence.
According to several epidemiological studies, Prevalence of respiratory allergies is estimated between 10-30% usually with a greater affected population in urban areas rather than rural ones (13)(14)(15).
Allergic Rhinitis (AR), the most common respiratory allergy disease with an increasing prevalence (16,17) is an inflammatory condition and is characterized by nasal symptoms such as sneezing, itchy, stuffy and runny nose (18,19). While it is usually considered a mild health issue, it can adversely affect patients' quality of life through direct and indirect complications and impose a heavy burden on the public health system (16,20,21). AR is also considered as a significant risk factor for allergic asthma, a chronic inflammatory respiratory disease characterized by reversible narrowing and hyper-responsiveness of the bronchial airway to a variety of biological and environmental stimuli with classic symptoms including wheezing, recurrent cough and dyspnea (22)(23)(24). Asthma usually coexists with rhinitis and is an important cause of chronic morbidity and mortality in the world (18,25).
Allergic Rhinoconjunctivitis (ARC) is also one of the most common chronic respiratory diseases and atopic disorders which has been less studied through the lens of epidemiology (26). Aeroallergens (airborne allergens) are important factors in respiratory allergies (3). Studies have shown that the distribution and pattern of aeroallergens significantly varies among different countries and even different regions within a country (27,28).
Iran is a large country located between the subtropical aridity of the Arabian Desert areas and the subtropical humidity of the eastern Mediterranean area with various geo-climatic conditions in its different regions. Mashhad, the second largest and populated city of Iran, is in the Northeast of this country and has a semiarid climate described with hot summers and cold winters (11,16). As the pattern of allergens prevalence may differ from time to time due to the environmental changes, the goal of the present study was to further investigate the most recent prevalence of aeroallergens in a larger population of patients suffering from AR, ARC, Asthma or a combination of these diseases during a 5 year period, in Mashhad, Iran using SPT in order to develop better management for respiratory allergies in different groups of people with different characteristics.

Demography
A cross-sectional study was done on patients, age 1 to    There is a significant difference in sensitivity to Salsola kali, ash, grass mix, pigweed mix, tree mix (p˂ 0.001), D.
pteronyssinus, (p=0.003), Birch tree (p=0.02) and cockroach (p=0.2) in different respiratory diseases with a higher prevalence among people with AR.  Cladosporium 0(0%) 0(0%) 0(0%) 0(0%) 0(0%) - farina, D. pteronyssinus and cockroach) were reported as the most common allergens (18). This contrast could be due to major climatic difference between two cities. Unlike Mashhad, Sari has a humid climate which makes the indoor areas more suitable for mites to thrive. Pollens were also reported as the most common allergens in neighboring countries such as Jordan (29) (34). Rhinorrhea and sneezing followed by pruritus and congestion were also reported as the most common symptoms of AR in the research done by Ghaffari et al. in Sari (18) which is the same as the results of the present study. They also reported cough, dyspnea and wheezing as the most common symptoms in patients with asthma (18) which is in contrast with present study. Although there was a higher prevalence of allergic diseases among patients with a family history of atopic disorder, no statistically significant correlation was found between these variables in the present study. There was also no significant correlation between gender and sensitivity to allergens which is in accordance with the studies done by Kashef et al. in Shiraz (35) and Farrokhi et al. in Bushehr (9). A significant relationship was found between AR and sensitivity to Salsola kali, ash, grass mix, pigweed mix, tree mix, D. pteronyssinus, birch tree and cockroach. A similar correlation between AR and ash, grass mix, pigweed mix, tree mix had been reported in Mashhad (11).

CONCLUSION
In conclusion, determination of allergen pattern and the rate of allergic patients' sensitivity to each allergen in each area are of great importance in controlling and treatment of allergic disorders. Salsola kali, pigweed mix, tree mix and ash were the most provocative allergens in Mashhad, Iran.